Signaling system



' Aug. 6, 1940. c. J. FITCH SIGNALING SYSTEM Filed Sept. 16, 1938 s Sheets-Sheet 1 RECEIVING DISTRIBUTOR 9 m w L T u T W 1 m J 7 w a LT Es a u W n T u 6 U 66 7 P m |v N T N mm s we R Aug. 6, 1940.

' C. J. FITCH SIGNALING SYSTEM Filed Sept. 16, 1938 3 Sheets-Sheet 2 ATTORNEYS Aug. 6, 1940. c. J. FITCH SIGNALING SYSTEM Filed Sept. 16, 1938 s Sheets-Sheet s ATTORNEYS Patented Aug. 6 1940 UNITED STATES PATEN OFFICE Application September 16, 1938, Serial No. 230,272

6 Claims.

The present invention relates to-si naling systems and more particularly to signaling systems utilizing signal distributing. means in the form ofan electronic distributing means adapted to be controlled in accordance with the provisions of the well known principles of the mechanical startstop signal distributors.

In the instant application the electronic distributing means comprises a plurality of electron 10 discharge devices arranged electrically so that the anode circuits in the preceding devices exercise control over the grid circuits of the succeeding devices. NormallyQthe electron discharge devices are maintained non-conductive until a control circuit of the electronic distributing means is conditioned in a predetermined manner, thus rendering the electron discharge devices conduc tive automatically in succession until the last device of the series is rendered conductive wherei upon the normal control conditions are igestored to render the said series of devices non-conductive, thereby preparing and conditioning the electronic distributing means for further signal conditions. i Provision is made in the present invention to condition signalingcha-nnels associated with the electronic distributing means so that at the particular time interval the said electron discharge.devices are rendered conductive, the signaling channels are adapted to be rendered effective for predetermined control purposes. I

One of the objects of the present invention resides in theprovision of control means for a plurality of electrically associated electric discharge devices adapted to be rendered conductive sucto control the initiation of .the progressive operation of the electric discharge devices.

Another object of the present invention resides in the provision of means whereby the electronic distributing means is adapted to be operated aperiodically, that is, adapting the electronic distributing means to be operated so as to simulate the action of the well known mechanical startstop signal distributing devices. An object of the present invention resides in the provision of means comprising signal transmitting and receiving means associated with electronic start-stop distributing means at remotely 50 situated stations to control the said distributing Fmeans for transmitting and receiving signals. Another object of the present inventionresides in the provision of means controlled by the sig nal transmitting means whereby upon operation 55 thereof the electronic distributing. means at the transmitting and receiving stations are rendered operative.

Another object of the present invention is the provision of combinational code transmitting and receiving control means associated with the elec- 5 tronic distributing means to control and be controlled by the respective electronic distributing means at the transmitting and receiving stations.

Still another object of the present invention resides in the provision of means to impress con- 10 tinuously upon the transmission medium during non-signaling intervals a system conditioning signal thereby maintaining the electronic-receivin distributing means inoperative until cessation of the conditioning signal occurs. 16

Still another object of the present invention resides in the. provision of means to render inoperative automatically the electronic distributing means at both stations upon completion of the signal transmission cycle. 20

Further objects ofthe instant invention reside in any novel feature of construction or operation or novel combination of parts present in the embodiment of the invention described and shown in the accompanying drawings whether within 25 or without the scope of the appended claims and irrespective of other specific statements as to the scope of the invention contained herein.

In the drawings:

Fig. 1 shows diagrammatically the circuit ar- 3o rangement for thepresent signaling system.

Fig. 2 shows one form of circuit arrangement of a suitable tone signal generating system.

Fig. 3 shows a circuit arrangement of the transmitting electronic-distributing means and specific associated control devices.

Fig. '4 shows the circuit arrangement. with the receiving electronic distributing means and the associated specific control circuits.

Before describing in detail the electrical ar- 40 rangement of the present electronic distributing -means and an exemplary type of specific control circuit arrangement which may be employed in association therewith, a brief and general description of the signaling system willnow be given.

General description Referring now to Fig.1. a diagrammatic ar rangement is shown embodying the electronic 3 distributing means indicated generally at I! and ll at the transmitting andreceiving stations re- C to"C5. The said contact means are provided to condition the signaling channels and electronic distributing means tO initiate independent' or dependent signals which are based upon a time division basis, that is, particular time valuesare imparted to the signals during predetermined timed intervals to difierentiate between the successively initiated signals.

The signaling vchannels obviously may be associated with a common control'device having interrelated control elements to control the conditioning of the independent signaling channels, or individual devices may be provided having unrelated control elements wherein independent control means are provided to condition simultaneously or aperiodically the signaling channels to control the initiation of the control. signals. Thus,

- for. example, the signaling channel control means,

namely, the contact means C--| to C--5 may be operatedindependently to condition the associated signaling channels and the electronic distributing means or maybe controlled'in predetermined or permutative combinations to condition the said associated signaling channels and electronic distributing means. 7

In order to simplify the description to follow, let it be assumed that the contact means 6-4 to 0-5 are controlled in accordance with well known permutation codes, that is, let it'be assumed that the contact arrangement designated C-l to 0-5 arecontrolled by well known types of keyboard control devices such as, for example, 4 the type disclosed in U. S. Patent 1,214,515 dated February 6, 1917, or if preferred it may be of the type shown in copending application Serial No. 113,798, filed December 2, 1936. Such forms of control devices are well known in the art and. since the control devices per se form no part of the present invention, further details and description are deemed unnecessary and thus are ,generally indicated in the said figure by the refereiice character ll.

The transmitting electronic distributing means generally indicated at I2 is shown in detail in Fig. 3 and comprises a series of electric discharge devices ST; ST-I, ST-2, etc. The individual devices ST--l to ST5 normally are maintained non-conductive until a predeterminedsignal'condition is adapted to condition the control device ST to render the remaining electric discharge devices conductive progressively in succession.

' Uponioperation of the last, devicein the series,

- tions are not transmitted to impress upon the transmission medium a continuous' signal or control means are provided to restore the series I of devices to the normal non-conductive condition until rendered operative at a later time upon further conditioning of the control device ST.

It should be mentioned in respect to the 'pres- 'ent application of the electronic distributing means to be outlined hereinbelow that further well known'signaling conditions are simulated,

namely, that the circuit arrangement is adapted j during the periods that character signal condielectrical condition. This signaling condition which may be applied to the transmission medium conforms tothe marking signal (current condition on the transmission medium) directly impressed upon the a I \the non-signaling periods in the present day printing telegraph signaling systems. Thus, it

' will be shown that upon conditioning'the control device ST the continuous control or marking signal impressed upon the transmission medium is discontinued, creating a zero current condition transmission lines during signal conditions are impressed upon the traris- 5 mission medium in accordance with the conditioning of the associated signaling channels.

3 In Fig. 1 a tone generator generally designated by thereference character i3 and shown in detail in Fig. 2 is shown interposed between the trans- 10 mitting "electronicdistributing means and the transmission medium' I0. It will be understood as the description progresses that for certain signaling applications the tone generator may be dispensed with and, instead of keying the tone 195 generator by the initiated signals, provision may be made to impress the said initiated signals directly upon the transmission medium. Associ= ated with the transmission medium at the receiving station is -a receiving electron distributing 20 means generally indicated in Fig. 1 by the referejrce character I. and shown in detail in Fig. 4. The receiving electronic distributor is shown to comprise a series of electric dischargedevices RT,

RT-I, RT2,\ etc. The dischargedevice HT is 25 employed as a control device for the remaining devices in the series, n amely,'RT-i to RT-5,

and is adapted to be operated similarly as the control device ST associated with the transmitting distributing means to control the sequential operation of the series of devices RT-l to RT-5. It will be seen that the operation of the said series t of electric discharge devices at the transmitting and receiving stations are similar in action. Specific control circuits are shown associated with the receiving electronic distributing -means to control the associated signaling channels which is shown to include the control means M,l to

M--5. The said-control means 141-! to M--5 may comprise individual control means for indi- 40 viduall'y associated and unrelated devices or, as statedin connection with the transmitting station, the said control means may form part of a common control device and be interrelated to control the common controldevice in accordance 45 with the signals impressed upon the transmission medium. To continue with the example set forth in connection with the transmitting station, the control means M--i to M-5 may comprise the individual control magnets adapted to be ener- 60 gized or controlled in accordance with well known permutation codes to control. a signal recording device a well known form of which is disclosed in U.'S. Patent No. 1,128,422, dated February 16, 1915, ing U. S.-application Serial No.'113,'799, filed December 2, 1936. In Fig. 1 the signal recording means is referred to generally by the reference character I 5; and as this mechanism per se forms no part of the present invention, it is deemed un- 50 necessary to describe it in further detail.

Transmitting circuit arrangement Referring now to Fig. 3, the electronic signal distributing means at the transmitting station is 65 shown to comprise a series of electric discharge devices ST, ST-i, ST,-2, etc. The individual discharge devices are shown to comprise a well known form of double triode type of electron discharge means. It is seen that one of the anode o circuits of the preceding tube is electrically coupled and adapted to control the input circuit of the next discharge device in the series. The grids 2l-25 of thedevices ST-l to ST-5 respectively are normally or may be of the type shown in the copendadapted to be .biased by the battery 26 and the grid biases are adapted to be of such values as to render the devices ST-I to ST-'-5 non-conductive. The grid 20 of the device ST is also adaptedto be biased by the said battery 26 to the same degree so that no current is permitted to flow in the associated anode'circuit. It. is to be noted that a variable resistor I8 is provided so that slight variations in the values of, the grid-bias for all the individual grid elements of the tubes, except the control grid l9,

may be effected. By varying the grid bias of the pressed upon the next succeeding devices by means of theassociated transformers T-Z, T-3, etc. In the primary circuits of the said transformers T--2 to T-S individual impulse delay means are incorporated in the circuits to delay the initiation of the following impulse which is to be impressed upon the next discharge device in the series by means of the associated transformer. The time delay means comprises the individual primary windings of the said transformers and the associated individual condensers 32-36.

Now assume that the switches S-l to 8-! associated with the power supplies designated A and B are closed. It is'seen that a circuit is immediately established permitting current to' pass from the positive'term'inai of the power supply B through resistor 31. and conductor 88athrough the primary winding of the transformer T l, anode 39 and the cathode of the device ST,'

to ,the negative terminal of the power supply B through the bias control resistor l8, creating a nected directly through the resistor l! to the-- cathode of the device ST, thus maintaining the grid bias value thereof at zero and permitting current to pass from the said anode 39 to the cathode of the said device under the conditions described.

It was mentioned-that the grid element 20 in the device ST and the grids 2l-25 of the devices ST---l to ST- were maintained at a normal negative bias so as to render the associated output circuits non-conductive. Thus far, it is seen 'that all the output circuits associated with the individual anodes of the said devices with the exception of the circuit associated with the anode 39 of the device ST are not energized ,nnder the present conditions. It should be mentioned that I the direction of the current flow through the primary winding of transformer T-'-l is such as to aid the negative bias potential impressed on grid set to be 0; anypredetermined cuit is established, the bias condition impressed on the grid 20 remains such so as to maintainthe circuit associated with anode 40 deenergize'd.

,Now assume for the moment that a negative, potential is impressed upon the grid circuit #9 of the device ST which, for example, occurs when the contacts CR-b associated with relay CR are closed, thus permitting the following circuit to be established: from the negative terminal of the .power supply A to conductor 5| contacts CRb (assumed to be closed), conductor 52, resistor l'l, conductors 63 and 54 to the positive terminal of the power supply A. Upo'n establishing the described circuit from the power supply A through the said contacts CR-b the direction of the current flow through the said resistor I1. is such as to impress a negative potential on the grid l9 of the device ST with respect to its cathode, which potential is sufllcient to bias the device ST preventing further current flow in the circuit connected to the associated anode element 39. Supp essing the flow of current in the circuit asso-' c ated with the said anode 39, it is seen that the signal condition impressed upon the terminals 38 and 39 is discontinued. Hereinafter the continuous' signal condition impressed upon the.terminals 38 and 39 and characterized assimilar to the continuous marking signal of the present printing telegraph systems will be referred to as the system conditioning signal. When the current flow is discontinuedv through the resistor 31, no difference of potential is impressed upon the terminals 38 and 39 or, in other. words, the con- 'ditioning signal no longer is impressed thereupon. This condition will be referred to as the starting ,signal and-corresponds to the zero current condition or spacing signal of .'the telegraph systems- ,referred to. s

It was just mentioned that the normal current flow through resistor 31 flows through the primary winding of the transformer T-i in the anode- 39 and cathode of the device ST. However, when this current flow is suppressed or cut oil, due to the potential drop impressed uponthe resistor ll upon closure of the contacts CRb, the sudden interruption of the current flow through the said primary winding of the transformer T-l causes the magnetic field thereof to collapse and generate animpulse whichisdmpressed upon the control grid 28 of the device ST through the secondary winding of the said transformer T|. It

was mentioned that normally the'grid element "is at a negative bias, thus preventing current to pass from the associated anode III to. the cathode of the device ST. The impulse generated, due'to the collapse of the magnetic field of the transformer T--| and impressed upon the grid 20,

is adapted to be in'a positive direction, thus overcomingthe bias impressed upon this grid by the battery 26 andthereby' permitting current to flow momentarily in the circuit connected to the associated anode 40. The circuit referred to associated with the anode 48 can be traced as follows. from the positive terminal of the power supply B -to the common conductor 55, primary winding of the transformer T-2 and the shunted condenser 32 to the anode and cathode of the device ST to the common conductor 53 and negative terminal of the said power supply. Since the impulse generated by the eollapse of the magnetic field in the transformer T-'l andimpressed upon the control grid 2il-is of short duratiomthe current similarly of short duration, and the time value element 20, sothat at the moment the said cirthereof is equivalent to the timed interval during 4 which the impulse is impressed upon the grid 20. The impulse generated by the transformer T-2 is retarded in phase 180 from the original impulse generated by the transformer Tl due to the impulse time delay means comprising the aperiodic'ally tuned transformer circuit. The impulse generated by the transformer T-'2 is initiated at a time duration later than the impulse generated by the transformer T-I but the time of initiation or generation is equal to the time duration of the impulse initiated by'the transformer T-l.

said grids in a positive direction, thus overcoming thenegative bias impressedupon the said grids 2I' by thebattery 26,thereby permitting current to flow in the circuit associated with the anode 42 of the device ST-|.

It .is seen that thecircuit associated with the anode 42 is similar to the tuned circuit arrange? ment associated with the anode l0. Thus, upon impressing the said "impulses upon the grids 2| of the device ST-l, thereby rendering the said i ilarly retarded 180 in phase with respect to the the transformer device conductive, current momentarily is permitted to flow in the following circuit: From the positive terminal of the comprising condenser 33 and primary winding of T'-3, anode 42 andassociated cathode of the device ST-l to the negatiye terpower supply B to the conductor 55 to the tuned circuit arrangement generated due to The described action is succession rendering in turn each of the sucaciomc upon the associated device is effective to regain control thereof, thus rendering the associated devices non-conductive until a further cycle is established by virtue of conditioning the control device ST in the predetermined manner just described, namely, to render one of the current ofthe device ST non-conductive, for example, by impressing a grid bias of sufficient value upon the associated control grid to prevent current flow in the associated anode circuit.

The cessation of the said system conditioning electrical condition generated by the device ST and impresseed upon the circuit associated with the anode 39 thereof is eifective to cause generation of the first control impulse which is of sufflcient value to overcome the. negative grid bias of the first device in the series of devices comprising the electronic distributing means, namely, discharge device ST-l.- A second'impulse is the conductivity of the said conducting paths first device of the series to render the next def vice in the series conductive. However, the initiation of the said second impulse is delayed by means of the tuned circuit arrangement interposed between the said first and second devices. effected progressively in ceeding devices conductive for a short timed inten/a1 corresponding to the time duration that minal in the said power supply. Cessation of current flow in this last described circuit is ef-' fective to generate and initiate another impulse which is impressed by means of the transformer T-3 in a positive direction upon the grids 22 of the device ST--2. The impulse initiated in this circuit, however, due to the time delay action of the tuned vcircuit, and impressed upon the co trol grid elements is retarded 180 in phase I impressed upon the grids respect to the impulse 22. Impressionof the positive impulseupon the grids 23 is effective to initiate still another impulse, since'the device ST-3 is rendered conductive so as to .energize the tuned circuit associated with transformer T- -5. Theimpulse initiated bythis last mentioned transformer is simimpulse impressed upon the device ST-3 to condition the grids 24 of the device ST-l, rendering this last mentioned device conductive and energize the tuned circuit associated with the transformer T-G to initiate, upon deenergization thereof, still another 180 phase retarded impulse which is impnessed upon-grids 25 of the device- ST-5 rendering thi last mentioned de vice conductive.

Thus, it is seen that the normally non-conduc-' to ST-5 arerendered con-'- tive devices ST- -l I ductive progressively in succession whenever the control device ST is conditioned in a predetermined manner. The sequential operation of the devices is eifectedby-the generation of the individual impulses which are adapted to overcome the effects of the individual grid biases impressed upon the devices to render the said devices conductive in succession. Immediately after the operation of each device,

. distributing means.

the impulse is impressed thereon. I

It was mentioned that upon operation of the last device in the series that the electronic distributing means is automatically restored to the normal inoperative state or condition, thus preparing the distributing means for further signaling purposes. One method of effecting this desired feature will now be explained. It was assumed that during the description of the successive operation of. the saidlelectric discharge devices the contacts CR-b were closed to eifect initiation of the progressive operation of the For the following description', at the moment, let it be assumed that the normally closed contacts SR-a upon operation are effective to open the control circuit including the said contacts CR-b until a later signaling operation, similar to the one just described, is

. desired to be effected. It is seen that the controlling relay coil SR which is adapted to operate the contacts SR-a is connected directly to the anode 50 of the device ST-5. Therefore, upon operation of this device ST-5, whichis the last one in the series, it is seen that the ,coil of relay SR is energized by-means of the following circuit which is established momentarily from the positive terminal of the power supply B to conductors '55 and 56, coil of the relay SR, anode 50 and cathode of the device ST.--5. to the negative terminal of the said power supply through the control resistor l8, thus energizing the said coil and thereby eflecting operation of the relay to open the contacts SRr- .The said contacts SR-a are included in-the gridbias circuit described hereinabove to impress a bias of suflicient value upon the control grid ls of the device ST to prevent current flow in the circuit connected to the associated anode 39 thereof. It was assumed that operation of the contacts SR-a is effective to cause the opening of the contacts CR-b unthe grid bias impressed til these last mentioned contacts are operated at a later time. 'Thus, itis seen that the negative biasis removed from the control grid I9 01 the device ST, thereby permitting current to flow in the associated anode circuit which as 75 traced hereinabove comprises the circuit from the positive terminal of the power supply B to the resistor 31, conductor38a, primary winding of transformer T-l, anode 39 and cathode of the device ST to the negative terminal of the said' power supply. Current flow in this circuit again establishes a difference of potential across the output terminals 38- and 39, thereby impressing upon the said output circuit the system conditioning electrical condition referred to hereinbefore. It is understood now that this electrical condition is maintained on the transmission medium associated with the terminals 38 and 39 until the contacts CRb are operated at some later time. The grid bias impressed upon the control grids of the remaining devices in the distributing means are effective during the nonsignaling periods to regain control, as mentioned hereinabove, of the devices, thus preventing these: devices from being conductive; In this manner it is seen that the electronic distributing. means is rendered operative for a predetermined timed interval and at the'end of this timed interval is rendered inoperative until at any later desired period the control device ST is conditioned in the predetermined manner as described hereinabove.

Eachof the ,said devicesST,l to ST-6 included in the signal distributing means is elecment will be now described.

trically associated with. individual signaling channels. .The control circuits of these channels comprise the individual circuits 6i-66 which are associated with the anodes 4|, l3, l6, l1 and 69 respectively andare conditioned in, succession upon operation of the devices ST--l to ST6 for control purposes. In ordento simplify the description, a specific signaling control arrange- Assume that the contacts C-I to 1 (L -5 are controlled permutatively by suitable signaling ap paratuswhich are well known in the art and similar to those fully disclosed'in the aboverei'erred to U. S. Patent No. 1,214,515 and copending application Seriah No. 113,798. Such signaling apparatus is adapted to control the operationof the contacts simultaneously in. various combinations representing diiferent dharacterizations. As-' sume now that the groupbf contacts designated -3 are operated momentarily to close the con- :tacts 66 and 67. Upon closure of the contacts 66 the following circuit is establishedfrom the negatives terminal of the power supply A through the normally closed contacts SBA-a, common.

conductor 51, normally closed contacts Cmc, contacts 66 now closed,

gzommon conductor :68,

normally closed contacts CR a, coil of therelay CR, conductor 52, resistor l1, conductors 53 and I v A to conductor 54 to the-positive terminal 0f the said power supply, energizing the coil of the said relay effecting operation of the associated contacts. 'Asshown in Fig. 3,'the Q0nt8.0ts C and CR-a are of the'make before break .typ Therefore, a cirto the positive terminal ofthesaid'power supply,

I thus energizing and operating" the said relay.

The contacts R-3b and R3a are of the make before break type so that a circuit from the said power supply is established through the fir-3b contacts to maintain the relay R3 energized until the normally closed contacts SR-a are opened. The contacts CR.c associated with the CR. relay are adjusted so that upon energizetion of the relay CR there is enough time lag in the operation of these contacts to permit the circuitjust describedto be established, namely, to

permit energization of the group of controlrelays 'R-l to R-5. It is seen that; when the contacts- CR-c are opened, the power supply is cut oil from the group of control contacts (2-! to 0-5, thus preventing operation of the signaling apparatus and any one of the contacts CAI to C5 to disturb the signal selection set-up until the end of the transmission cycle, that is, until the signals representing the selected character are transmitted by the electronic distributing means. Closure of contacts R.-3c connect.conductor..63 and anode 45 of the device ST3 by means of the common conductor 69 to the output terminals- 38 and 39. Therefore, it is seen upon operation of the group of contacts identified as C3, the

' said output circuit of the device ST-3 is conditioned or completed for energization whenever the device ST-3 is rendered conductive. J It was mentioned hereinabove that upon clocontrol grid element l9 of the device ST, this circuit which was traced, is effective to establish a bias upon the said control grid element of such value so as to prevent current to flow in the outsaid device. It is understood now that under these conditions the potential difference impressed across the output terminals 36 and 39 nolonger exists and that hereinabove this condition sure of contacts Cl't-b permitting voltage to be impressed upon. the circuit associated with the I put circuit associated with the anode 39 of the I 0.

at this time was referred to as the starting signal condition; It' was also described in detail herein above that the collapse of the magnetic field in the-transformer T-l momentarily generates an impulse in a positive direction overcoming the grid bias impressed upon {the grid element 20 of the device ST and that at this moment current is permitted to fiow in the circuit associated with the anode 40 of the said device. -Dueto this current flow, the transformer I -2 is energized and by means of the described time delay means associated therewith animpulse is generateda'nd initiated, retarded 180 in phase with respect to the impulse originated by the transformer T-l.

The impulse initiated by the transformer 'r i is effective to render the device S'Ie-J conductive,

which in turn energizes the transformer T3 andsubsequently renders the device ST2 .conductive, in turn energizing transformer If-4 rendering the device ST3' conductive at'a later timed interval and energizin-gf the transformer T-5 and rendering the device ST'4 conductive which in turn energizes the transformer T-r6 to render the last device in the series $T -6conductive, It is seen that since the contacts Rlc and R 2c,v remain open at the time the device ST- -l and S T-Z are rendered conductive, no"

signal conditionsca'n be initiated by the said devices when rendered conductive, thus maintaining'the transmission, medium, connected to the terminals 38 and 39, unenergizedat these particular timed intervals in the transmission cycle.

However, when the-device ST3 is renderedoperative due is the impulse generated and initiated by the transformer T-'-4,' a signal at this particular timed interval is impressed upon the output terminal 38 and 39 by means of the followingcircuit which is established momentarily: from the positive terminal of the power supply B to the resistor 31, conductor 69, contactsR-Jc, conductor 63, anode l5 and cathode of the device ST3 to the common conductor 53 and the negative terminal of the said power supply throughthe control tial difference across to the current flow through the resistor 31, thereslgnal condition impressed upon the output terthe signaling cycle. It was ass minals. Since the contacts R.-3c are the only contacts closed fqr the example chosen, a signal condition is only transmitted at the timed interval the device ST-.3 is rendered conductive. However, it is obvious that various combinations of signal conditions can beimpressed upon theoutput terminals depending upon the specific combinations of control contacts operated durin mentioned that upon operation of the last device, namely, ST-5 in the series that the relay SR is energized and operated to open the associated contacts SR-a. Operation of these last mentioned contacts is effective to open the holding circuits for the relays R-3 and CR. Deenergization of the said relays re-.

stores the nomial conditions as described herein above and as shown in :Fig. 3.

It is remembered that, when the normal conditions referred to are restored,the negative grid bias impressed on the control grid IQ of the device ST is removed therefrom, permitting current to flow immediately in the circuit associated with the anode 39, thereby impressing the continuous signal condition upon ,the output terminal 381 and 39 and which has been referred to as the system conditioning signal. .The "electronic distributing means is now conditioned for further signaling.

purposes upon operation of the associated signaling apparatus and control circuits, namely, the group of contacts C-l to 0-5 and control relays R,--l to R and the associated control circuits. In this manner it is. seen that the .electronicfsignal distributing means is rendered operative autpinatically'upon operation of the signaling apparatus and by means .of the intercomnecting control circuits between the electric discharge devices of' the distributing means of the device ST-l to ST--i are rendered conductive automatically in sequence to permit any. of the conditioned signaling circuits or channels, by the respective contacts C-I to 0-5," to. impress corresponding, signal conditions upon the output" terminals 38 and n that. automatically upon operation of the last device of'the series that the con- 395 It is also ditioned' signa ng apparatus is restored to thenormal unconditioned state and that the electronic signaling distributing means is rendered inoperative until subsequent operation of the sigi aling apparatus. "During the nomaignahns.

resistor [8, thus impressing a potenthe terminal 38 and 39 due the impulse generated periods, that is, when the electronic distributing means is inoperative, a is continuously impressed upon the output terminal 38 and 39. It is also seen that upon operation of the signaling apparatus and after the desired character selection has been effected due to the circuit arrangement of the associated control means the further operation of the signaling apparatus during the signal transmission cycleis inefiective to eiiect or destroy the selected and stored character selection previously set up. Due to the described circuit arrangement of the control means, the signaling apparatus isnot effective to set up a new character selection until the end of the signaling cycle.

steady electrical condition Tone signal generator Y device Hi and the associated circuits which are arranged so that the oscillator system is continuously in an oscillating state. Part of the energy from the oscillating system is impressed by means of transformed upon the control grid elements ofthe electron discharge device 12. The device 12' comprises a double triode type of device and the control grid elements of which,

secondary or output winding of the oscillator system transformer II. The energy generated by the deviceyglz is impressed upon the associated push-pullrintput transformer I3, the secondary winding of which is connected to the output ter- .minals l4 and 15. The discharge device 12 isarranged so as to be controlled by the character impulses initiated by the transmitting circuit arrangement just described and in such a manner that, when the normal line signal or electrical condition is impressed on the .output terminals 3,8 and 39 of thetransmitting circuit (the normal line signa] condition is the system .conditioning electrical"condition referred to hereinabove), the v bias potential impressed on the grids of the.de-

vice I2 is such that the device 12 is conditioned to be conductive, permittlnga tone signal to be impressed upon the output terminal 14 and 13. However, when the conditioning signal removed from the line, that is, when the signal no longer the circuit arrangement \discharge circuit 1 are connected in push-pull relationship to the is 'impressedlupon the terminals "and" (for example, when the starting signal is transmitted) the device 12 is adapted to becontrolled' so as to be non-conductive by impressing grid bias po- 'tential upon the control grid elements of the device, so that thereis no current flow in the output circuits thereof, thereby discontinuing the tone signal impressed upon the/output terminal I4 and 15. This grid element biasingarrangement can 'be' effected in'- the following manner.

n'singl'e wave rec tying device the cathode elem t of'which is connectedto a point lie on the voltage divider and the anode elementsof which are connected through resistor 14a is provided} lito'the terminalsI'I-andll 'It'shouldbe men- I 'I tioned at this time that the input terminals 1-1 and-18 are connected directly tothe transmitting F 2,210,676 circuit output terminals 38 and 33 respectively as 18, it is seen that the anode elements of the device "care provided with a negative potential with respect to the cathode thereof equal to the voltage drop across the resistor 30 of the said voltage divider. 'A- mid point connection is provided from the secondary winding of the transformer II to the anode elements of the device 14a and due to this arrangement the grid control elements of the device 12 which are connected in push-pull fashion to the said secondary winding are provided with a negative potential with respeet to the cathode thereof which is connected to a point 8| on the voltage divider. Thus, the negative bias potential impressed on the grid elements of the device 12 is equal to the sum of the voltages across the resistors 80 and 82. This voltage value is sufilcient to bias the grid elements of the device 12 so as to render the said device nonconducti've, thereby preventing the energy from the oscillator system impressed directly on the winding of transformer ll to be impressed upon the output terminal ll and II:

Now, whenever the normal line signal, such as the system conditioning signal or the' character signals, are impressed upon the terminals 33 and. and TI and 13 respectively so that the polarity corresponds to that shown in Fig. 2 (and so thatthe voltage value. thereof is equal in amplitude to the voltage drop across the resistor 30), the rectifying device Ha will be rendered conductiveand the bias potential on'the grid elements of the device 12 will, then be equal to the voltage dr p across the resistor 82. The voltage drop acro s resistor 80 has been nullified by the signal voltage on the input terminals 11 and 18. Resistor 82 is of such value that thevoltage drop'across it is adapted to provide a bias potential for the gridelements of the device I2 so that this device is rendered conductive and operates in a manner similar to the class A type of amplifier, thereby permitting the output energy of the oscillator circuit to be amplified and impressed upon'the output signals It and I5. If the voltage of the signal conditions impressed on the input terminals 1'! and 13 is'oi' greater value. than the drop across resistor 80, current is permitted to hot? through the resistor 16 and the rectifying device llaand resistors 80 and 31.

, However, resistor lt' is of such relatively high value that said current flow is limited to such small value that the voltage drop across 'the rectifying device is negligible so that this volt- -age drop which opposes the voltage drop across resistor 82 is so minute that'for practical purposes the class A bias potential established for the tube 12 is not effected or altered sufliciently to effect the action or operation offthe device 12.;

amplitude, there will be reproduced tone signals of uniform amplitude in the signal output circuit represented by the terminals 14 and I5, providing however that the minimum amplitude of the signals on the input terminals ll, 18 is never less than the voltage drop across the-resistor 30.

In accordance with this circuit arrangement, it is seen that, whenever electrical conditions representingeither a system conditioning signal tone signal generator circuit arrangement is conditioned to permit the tone signals to be impressed upon the. output circuit terminal 14, 15, and it is seen that; whenever the signal conditions are not impressed upon the output terminals 38 and 39 of the transmitting circuit, the tone signal generator circuit arrangement is conditioned so that no tone signals are permitted to be impressed upon the output terminals 13 and 15.; With this arrangement .it will be evident that the same signaling conditions will prevail at the receiving station whether or not the tone minals 38 and 39.

. Receiving circuit arrangement ing distributing means is shown to comprise the control electrondischarge device RT and a series of electron discharge devices RT I to RT-S. Thedischarge devices utilized in the receiving circuit a e'gcf the double triode type similar to those employed in the transmitting circuit arrangement. The method of generating the'conor character signals are impressed upon the transmitting circuit output terminals 38, 33, t e

" Referring now to Fig. 4, the electronic receivtrol impulses to control the sequential operation ,of the discharge. devices RT--i to RT----! is con'nection with the transmitting circuit arrangement and shown in Fig. 3. For this reason it is deemed unnecessaryto repeat at this time the detailed method of'generating and initiating the individual phase retarded impulses which are It is who noted, however, that all of the grid I impressed upon the input terminals 84 and of the receiving circuit). A full wave rectifying device 95 is shown to be electrically associated with the input terminals and 85 of the receiving circuit. Whenever the tone signal generator is employed, the"full ,vyav rectifying device 35 is provided in the receiving circuit in order to impressed progressively upon the series of devices rectify the tone signals impressed upon theterminals 84 and 85. Upon rectification of the tone signals and as lgfig as the tone signals are impressed upon the input terminals of the receiving circuit, a continuous voltage is impressed tem by means of the connection thereof with v the resistor 96. It should be mentioned, however, that, whenever signal conditions are not impressed upon the input terminals 84 and 85,

' the said power supply. However, the bias popermit current to flow in its output circuit, they 4 'of the control device vice and the remaining tential impressed upon the said grid element is adapted .to be coufnteracted by the voltage impressed across the resistor 00 whenever signal conditions are impressed upon the terminals 04 and'85. Assuming now that the system condi-' tioning signal is impressed continuously upon said input terminals of the receiving circuit and 'that the rectified voltage impressed upon the resistor 96 is effective to overcome the grid bias,

potential impressed upon the control grid of the device 91 so that this said device is rendered conductive. Now, since the device 91 is adapted to following circuit is adapted to be energized and can be traced from the positive terminal of the power supply D to the conductor l0i, anode and cathode'elements of the device 91, conductor E02,

normally closedcontacts R-'I0b, primary windingof the first sequence coupling transformer TT-I to the negative terminal of the power supply through the resistor I03. Thus, whenever the tone signals are impressed upon the termi-Y;

nals 84 and 85, the device 91 is conditioned to permit current'to flow through the primary winde ing of the first sequence transformer 'I'I-I 'Current flow, however, when first established through the primary winding of. transformer TT-i at this time. isnot effective to overcome the bias potential impressed upon the grid elements 86 RT so that this control deto RT-5 in this series remain non-conductive. 'I'he'reason forthis is that the directionof the current fiow'through the primary winding of transformer 'I'I-l is such as'to aid the negative bias potential'pn the grid element 20. However, whcnthe incoming signals are no longer impressed upon the input terminals 84 and 85, which is the asewhen the starting or character signals are transmitted,-the device 91 is instantly controlled, by the grid bias potential impressed thereon so as .torender the device note-conductive and due to the interruptioii of'the current flow throughfthe primary winding of-the transformer Y T'I-I; the magnetic field thereof is caused to collapseresulting in an impulse in a positive direction which is impressed upon the grids 06 of the device .RT' through the secondary winding of the transformer TIT-4. (The impulse generated] by the said transformer is of sufficient value to overcome momentarily the bias potential impressed uponthe said grids 86 so as to render .the device-RT conductive. It is noted-that the anode element I00 ofthe" device RT is connected to the primary winding of the/transformer TT--2 so that, whenfltlie device RT is rendered conductive, -the said 'transformer is adapted to be energized by means of the circuit from the positive'terminals in the power supply'D to the time delay circuit means comprising the primary wind- I of the transformer 'I' I-2 and the condenser associated therewith to the anode I06 a d This biasing circuit circuit arrangement.

discharge device RIF-I ode of the device RT to the negative terminal of the said power supply. Upon cessation of the current flow in the primary winding of the transformer TI -2, an impulse is generated in the Y secondary winding thereof retarded 180 in phase with respect to the impulse generated by the transformer -TT--i to overcome the bias on the grid elements 81 of the device RT-I torender this last mentioned device conductive. Individual phase retarded impulses are then sequentially generated and initiated by the remaining transformers of the series 'I'T.-3 to IT-0 to render the'remaining associated devices RT--Z to BIT-"5 conductive progressively and insuccession similarly as described in connection with the devices 'ST-l to-ST5 with respect to the transmitting The transformers TT-I to IT-0 have the same inductance, capacitance and resistance values as those of the transformer T-l to -T--6 of the transmitting distributing means so that the time duration of the individual impulses generated and the time duration of the cycle of operatioh of the electronic distributing means is the same as'that of the trans mitting electronic distributing means,

that is to say, when the device ST--I of the transmitter is rendered conductive to initiate signal condi- "tionswhich are impressed upon the input terminals 84 and 85 of the receiving circuit, the device RT -I is rendered conductive so as to be controlled by the said signals so initiated. The actionof the'devices ST--2 to 8T5 and RT-Z to RT-5 are similarly controlled so as to be ren-. dered conductive or operative at thesame exclusive intervals duringthe transmitting and receiving cycles. I

, Fromthe description up to this point, the operation of the electronic signal distributing means perse should be'understood so that further detailed description of the receiving electronic distributing meansis not deemed necessary. Therefore, the specific control circuits and signal selection circuits will now be described.

When the first control impulse, caused by the collapse of the magnetictfield of the transformer T'I'p-J is impinged on the grids 86 of the device RT, rendering this device conductive, current is also permitted to-flow in the circuit connected to the sociated anode I05 which may be traced as follows: from the positive terminal of the power supply D to the common conductor. IN, to

the" pick-up coil H0 'of therelay 'R--i0, anode I05 and cathode of the device BT to the negative terminal of the saidpower supply, thus en ergizing the said pick-up coil and operating the relay Rr-IO to open the normally closed'contacts' R},I 0b and closing the contacts RI 0a.; A hold-. ing circuit for the said relay is immediately established through the associated closed contactsand can be traced from the positive terminal of the power supply C through the normally closed contacts R-I 6c, conductor I30,- contacts R- l0a,

holding coil I20 of relay R-+I0 to the common conductor I3I to the negative terminal of the said power supply. Therefore,'- it is seen that imtrol impulse of" the electronic distributing means, due' to the collapse of the magnetic field or the transformer {I'll-l, relay\R-I0 is adapted to be operated and maintained operated by means of mediately'upon the generation of the first conthe holding circuitjust describedcuntil the 'normally closed contacts Bi -46c are opened which occursat the end ol'ithe transmission cycle and will be explained laterh rein. The control relays R-II to R- I G are imilarly provided with v 2,210,578 pick-up was ill to m and holding coils m to I 26 for the same purposes.

It is seen that, when the contacts R-lb are opened, due to the energization of relay R-IO the cathode element of the discharge device 91 is disconnected from the primary winding of the transformer TT-I. It is evident that this condition exists as long as the said contacts are maintained.

.in an operative position by the relay' R -I0.

Therefore, due to this arrangement, furthersignal conditions impressed upon the terminals 34 and 35 cannot be impressed upon the primary of the transformer TT-I to effect generation and initiation of additional control impulses to eflect faulty operation of the devices RT, RT--l to RT--5- of the series.

In order to explain how the timed character signals transmitted and'impressed upon the input terminals of the receiving circuit are segregated for control purposes at the receiving station, it will be assumed that the character signal described to be initiated by the transmitting circuit arrangement under control of the group of contacts C3 is impressed upon the input terminals of the receivingcircuit. It will be remembered in connection with the description of the transmitting circuit arrangement that upon op eration of the group of contacts (7-3 the continuous signal impressed upon the terminals 38 and 39 thereof was discontinued to effect initiation of the 'so-called starting signal, and that further signal conditions were not impressed upon the terminals 33 and 39 until the time interval that the device ST-3 was rendered operative. Therefore, it is understood for the particular example described in connection with asinglecycle of operation of the transmitting circuit that the following electrical signal conditions were created, namely, to interrupt the continuous electrical signal condition impressed upon the terminals 38 and 39, which is referred to as the starting signal condition which was then followed by an electrical signal condition initiated during. let us say, a third timed interval of the trans mission cycle when the device ST3 was rendered operative "followed by the normal line signal condition or systemconditioning signal at the end of the. transmission cycle.

Upon receipt of the first said signal conditions referred to as the starting signal, the device RT is rendered operative to operate the relay R-Ill and cause the progressive operation of the -re- It was explained that during the signaling cycle, 1

" that is, when the electronic distributing means at the transmitting station and the receiving station are rendered operative progressively, the oath-- ode elementof .the device 91 is isolated from the primary winding of the transformer 'I'II and that due to this arrangement the grid potential impressed upon the grid element of the-device 31 is eflective to regain control of the device rendering it non-conductive whe er signal conditions are not impressed upon the input terminals [land 35 of the receiving circuit during the transmitting and receiving cycle. Now let it be assumed that the character signal initiated by the operation of the device ST--3 of the transmitter is received and impressed upon the input terminals of the receiving circuit which, as explained before, occurs at the time that the control impulses generated by the transformer TT4 and impressed upon the grids 89 of the device RT-3 render this last-mentioned device conductive.

.Receipt of the said character signal condition. is

inoperative. timed intervals when the devices RT4 and effective to cause the voltage drop appearing at this moment across the resistor 96 to neutralize or .counteract the grid bias potential impressed upon the control grid element of the device 91 to condition the said device so as to be conductive. Due to the conditioning of the device 91 in the described manner, at this particular timed interval current is permitted to flow in the circuit which may be traced from the positive terminal of the power supply D to the common conductor IIII, anode and cathode of the device 91, common conductor I 00, pick-up coil I I3 of relay R I3, anode I01, and cathode of the device RT--3 to the negative terminal of the power supply, thus energizing the said pick up coil and causing the operation of relay R-I3. A holding circuit for the said relay is immediately established and extends from the positive terminal of the power supply C to the normally closed contacts R-I'Ia, common conductor I32, contacts R-l3a now closed, holding 'coil I23 of thesaid relay to the negative terminal of the said power supply, maintaining the relay R,I3 operative until the normally closed contacts R-lla are opened at the end'oi' the distributor cycle.

It is understood that at the timed intervals the device RT-l and RT2 are rendered operative for the specific example chosen, current flow in the output circuits of the said devices which are associated respectively with the pick-up coils III and II! of the relays RH and R-IZ is suppressed, since the device 91 .at these particular timed intervals is adapted to be non-conductive,

due to the fact that signal conditions are not impressed on the input terminals 84 and 85 at these particular timed intervals, thus permitting the grid bias to control the device 91 so as to be This same condition exists at the RT-5 are rendered conductive. Therefore, the associated relays R-M and R-I5 remain inoperative during this said distributor cycle.

It will now be seen that, when the last' discharge device RT5 of theseries is rendered conductive, provision is made to not only restore the electronic distributing-means at the receiverto the normally inoperative state but that provision is also made to permit the conditioned and selected signaling channels to be effective for control purposes.

One method of effecting these features is to provide for the energization of the relay R-r-I' when the last device RT'-5 in the series is rendered conductive. In accordance with this provision the pick-up coil N6 of the said relay is adapted to be energized at thistime by means of the circuit established from the positive terminal ofthe power supply D to the commonconductor IIII; pick-up coil I II, anode I08 and cathode of the device RT5 to the negative terminal'of the now closed, holding coil I26 of the relay RI3 to the negative terminal of the said power supply, thus'm'aintaining the said relay operated until 'the contacts R-Ila are opened. Immediately upon operation of the relay RI6, theholding circuit for the relay Rl 0 is adapted to be broken due to the openingoi the contacts R-l6c'associated with the relay RI6. Deenergizatlon of the relay R l,0 causes the contacts R|I|b tobe closed, thereby permitting the system conditioning signal which is initiated upon completion of the cycle of operation of the transmitting electronic distributing means to beefiective to againrender the device 91 to be conductive and permitting the current in the anode circuit thereof to flow through the primary of the transformer TT-l similarly as described hereinbefore. Thus, the receivng electronic distributing means is maintained in an inoperative state until subsequent cessation of the current flow through the primary winding of the transformer IT-i, which as now understood is effective to generate the progressive operation'of the electronic distributing means. The receiving dstributing means is now conditioned for the reception and segregation of subsequent character signals.

At the same time that the relay R-ili is de-- energized a circuit is established through the contacts R-lfib to effect energization of the selected control means of the group M-| to M-5. Since relay R-IB is the only relay operated during the operation of the receiving distributing means in the example chosen, the control means M-3 is the only one energized by means of the closed contacts R,--l3b. It is understood that, whenever different combinations of the control means are selected and conditioned for energization due to the operation of the associated control contacts R-l lb to R-| 5b, the selected control means are adapted to be energized simultaneously for control purposes upon closure of the contacts R-lib.

It was mentioned hereinabove that the control means Ml to M-5 may be associated with individual 'signal receiving devices or may be associated with a common signal receiving device similar to the apparatus referred to and disclosed-in U. S. Patent No. 1,128,422 and the copending application Serial No. 113,799. Upon closure of the said contacts Rr-JFU effecting energization of the selected signal control means,

a circuit is established through the said contacts to the coil of relay R-ll to energize this relay. The time interval required tosufliciently energize this relay so as-to be operated to open the associated contacts Rl'|a is such that the operation thereof is not effected until sufllcient time has transpired upon closure of the contacts R-itb to effect energization of the selected control means of the group M-lto M-5. Upon oper-- ation of the relay Rr-I', contacts R,I'Ia are opened to break the holding circuit to relays R-i3 and R.-l6, thus restoring the said control relays to the normally deenergized condition as shown in Fig. 4. Upon deenergization of the relay RP-IS, currentsupply is disconnected from the coil of relay RF-I'I due to the opening of contacts R,l6b, thus causing relay R-l'l to be deenergized thereby permitting the associated contacts R-i'la to be closed and thus conditioning the'control circuit arrangement just described for further signaling channel selection purposes upon receipt of the subsequent character signals.

Thus, it has been shown that by means of the electronic distributing means and upon receipt of the timed signal conditions that signaling c'hannelsare selected in accordance with the control signals, and that theselected signaling channels are conditioned for control purposes, in a manner so .that upon completion of the distributing ortransmission cycle the said selected channels are energized thereby effecting control over the associated control means such as the magnets M-l to M+5 indicated in Fig. 4. It has also been shown that immediately upon exercising this control over one said control means that the electronic distributing means and selecting signaling channels are restored to the normal inoperative condition or state as shown in the figure for further reception of the selecting signaling conditions.

While there has been shown and described and pointed out the fundamental novel features of the invention as applied to a single modification it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. A signaling system comprising a transmitting station including signal transmitting means and a receiving station including signal receiving means, normally inoperative signal distributing means at each station comprising a series of electric discharge devices, means controlled by any ing control signals, means controlled by the distributing means at the receiving station for controlling the signal receiving means in accordance with the'control signals received, and means for rendering the said distributing means at the sta-, tions inoperative upon the operation of the last devices; in the said series thereby restoring the distributing means to the normal inoperative state for further signaling operations.

a 2. A signaling system comprising a transmitting station including a plurality of signal sources and a receiving station including a corresponding plurality of signal receiving means, normally inoperative signal distributing means at each station comprising a series of electric discharge devices, means for initiating" operation of the said distributing means at both stations in-' cluding meanscontrolled by any one of said signal receiving means in accordance with the si nals initiated by the signal sources.

3. A signaling system comprising a transmitting station including/a plurality of signal sources, a receiving station' including a corresponding plurality of signal receiving means, normally inoperative signal distributing means at each station comprising a series of electric discharge devices, means controlled by any one of the said signal soinces for initiating a start signal condition, means at eachstation responsive thereto for rendering the signal distributing means that operative, each said distributing means including means for rendering the said devices conductive successively at mutually exclusive intervals, means also controlled by the signal sources for controlling the initiation oi! control signal conditions upon operation of the distributing means at the transmitting station, and means controlled by the distributing means at the receiving station for controlling the corresponding signal receiving means in accordance with the signals initiated under control of the signal sources.

4. A signaling system comprising a transmitting station including a plurality of signal sources, a receiving station including a corresponding plurality ,of signal receiving means, signal distributing means at each station comprising a series of electric discharge devices, means at the transmitting station for transmitting "a; conditioning signal condition and means responsive thereto for normally maintaining the said distributing means at both stations inoperative, means controlled 'by the said signal sources for eil'ecting cessation of the said signal condition and means controlled thereby for rendering the said distributing means at'both stations operative, each said distributing means including means for rendering the said devices conductive successively at mutually exclusive intervals,

means also controlled by the signal sources for controlling the initiation of control signal conditions upon operation of the distributing means at the transmitting station, and means controlled by the distributing means at the receiving station for controlling the corresponding signal receiving means in accordance with the signal conditions initiated under control of the signal sources.

, 1 1 5. The invention set forth in claim 4 including means for establishing the said conditioning signal condition upon operation of the last devices in the said series whereupon the said means responsive thereto is again efiective to render the distributing means at both stations inoperative.

6. A signaling system comprising a transmitting station including a plurality of signal transmitting channels, a receiving station including a corresponding plurality of signal receiving channels, signal distributing means at each station comprising a series of electric discharge devices, means for selecting certain signal transmitting channels for controlling the initiation of the signals including means for maintaining the said selection for a predetermined timed interval, means controlled by any one of the selecting means for initiating operation'of the distributing means at both stations, each said distributin means including means for rendering the said devices conductive successively at mutually exelusive intervals, means controlled by the distributing means at the transmitting station for transmitting signals in accordance with the selected channels, means controlled by the distributing means at the receiving station for selecting the corresponding signal receiving channels, means at the transmitting station for wiping out the said channe1 selections maintained upon operation of the last device in the said series thereat, and means at the receiving station for rendering the selected channels thereat effective for control purposes upon'operation of the last device of the series thereat.

CLYDE J. Fwron.

' Patent No. 2,210,576.

CERTIFICATE OF CORRECTION.

i August 6, 19L .O CLYDE FITCH. H

It is hereby certified that error appears 1:; the printe l specification of the above numbered patent requiring correction as follows: l age 1O, sec-- ond column, line 714., claim 5, for the word "that" read --thereat--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in-the Patent Office. Signed and sealed this 10th day of September, A. D. 19140. I

Leslie Frazer,

(Seal) Acting 'connnissioher of Patents. 

